- The Symptom Checklist-90-Revised (SCL-90-R) The Symptom Checklist-90-Revised (SCL-90-R) will be used to assess psychological distress (Derogatis 1983). SCL-90-R is a 90-item questionnaire measuring psychological distress over the past week. Reliability and validity of the measure is found to be high. The Global Severity Index (GSI) is used as a measure of overall psychological distress. The SCL-90-R has been used in several previous MBSR studies to measure psychological status (Kabat-Zinn, et al. 1992; Kabat-Zinn, et al. 1985; Kabat-Zinn, et al.1987; Kaplan, et al. 1993; Miller, et al. 1995; Majumdar, et al. 2002).